Switched mode power supplies (SMPS) are widely used to supply voltages in applications such as televisions, freestanding mains adaptors, but also mobile communication devices. A conventional SMPS unit comprises a feedback loop, which controls a power transistor stage to produce the desired output voltage. The feedback loop controls, for example, a duty cycle of the power transistor stage. The SMPS unit additionally comprises a compensation network comprising a circuitry, which optimises the performance of the SMPS unit and enables the SMPS unit to have good linearity and stability properties.
The SMPS unit is typically implemented as a single integrated circuit in which case the characteristics of the compensation network are fixed but the output voltage may be changed adaptively. In such cases, the SMPS unit is dedicated to a given application. To provide the SMPS unit with more flexibility, the integrated circuit is provided with additional pins to which external tuning components may be attached. This is, however, a very cumbersome solution and limits the usability of such an SMPS unit in applications where different signal responses are needed for instance in an amplitude signal path of a radio transmitter based on envelope elimination and restoration (EER) architecture and/or in some other general applications experiencing variable load conditions. Furthermore, tuning the SMPS unit with external components increases the costs but also, from the electrical performance point-of-view, the sensitivity to noise.